plugin doesn’t work with php5

Hello! I recently upgraded my server to php5 and have found a plugin that quit working. I’m personally not incredible with php so I don’t know what could be causing this issue. Maybe someone here can look over this and see if there is anything huge that would be causing it to not like php5?

Thanks!!!

<?php
/*
Plugin Name: Custom Fields Permalink
Plugin URI: http://tec.toi-planning.net/wp/custom-fields-permalink
Description: This plugin enable to make a permalink from custom field's value.
Author: toiplan
Version: 0.1.0.0
Author URI: http://tec.toi-planning.net/
*/

function _custom_fields_permalink_replace($post, $key, $or) {
	$value = get_post_meta($post->ID, $key, true);
	if ($value) {
		return $value;
	}

	switch ($or) {
	case 'post_id':
		return $post->ID;
	case 'postname':
		return $post->post_name;
	default:
		return '';
	}
}

function custom_fields_permalink_filter($permalink, $post) {
	return preg_replace(
		'/%cfp_([^%]*?)(_or_(postname|post_id))?%/e',
		'_custom_fields_permalink_replace($post, "$1", "$3")',
		$permalink
	);
}
add_filter('post_link', 'custom_fields_permalink_filter', 10, 2);

function custom_fields_permalink_post_rewrite_rules(&$value) {
	$keys = array_keys($value);
	$tmp = $value;

	$value = array();
	$len = sizeof($keys);
	for ($i = 0; $i < $len; $i++) {
		$k = $keys[$i];

		if (preg_match('/%cfp_([^%]*?)(_or_(postname|post_id))?%/', $k)) {
			$nk = preg_replace(
				'/%cfp_([^%]*?)(_or_(postname|post_id))?%/',
				'([^/]+)',
				$k
			);
			$value[$nk] = preg_replace(
				'/%cfp_([^%]*?)(_or_(postname|post_id))?%/',
				'cfpk=$1&cfpo=$3&cfp=',
				$tmp[$k]
			);
		}
		else {
			$value[$k] = $tmp[$k];
		}
	}

	return $value;
}
add_filter(
	'post_rewrite_rules', 'custom_fields_permalink_post_rewrite_rules', 10, 1
);

function custom_fields_permalink_query_vars(&$value) {
	array_push($value, 'cfp', 'cfpk', 'cfpo');

	return $value;
}
add_filter(
	'query_vars', 'custom_fields_permalink_query_vars', 10, 1
);

$GLOBALS['custom_fields_permalink_processing'] = false;
function custom_fields_permalink_request(&$value) {
	if ($value['cfp']) {
		$cfp = $value['cfp'];
		$cfpk = $value['cfpk'];
		$cfpo = $value['cfpo'];
		unset(
			$value['cfp'],
			$value['cfpk'],
			$value['cfpo']
		);

		global $wpdb;
		if (! $cfpk) {
			return;
		}

		$ids_meta = $wpdb->get_col($wpdb->prepare(
			"SELECT post_id FROM $wpdb->postmeta WHERE meta_value = %s AND meta_key = %s", $cfp, $cfpk
		));

		$col = '';
		if ($cfpo == 'postname') {
			$col = 'post_name';
		}
		else if ($cfpo == 'post_id') {
			$col = 'ID';
		}

		if ($col) {
			$ids_posts = $wpdb->get_col($wpdb->prepare(
				"SELECT ID FROM $wpdb->posts WHERE $col = %s", $cfp
			));
		}
		else {
			$ids_posts = array();
		}

		$ids = array_merge($ids_meta, $ids_posts);
		if ($ids) {
			$GLOBALS['custom_fields_permalink_processing'] = true;
			$value['post__in'] = $ids;
		}
		else {
			$GLOBALS['custom_fields_permalink_processing'] = false;
			$keys = array_keys($value);
			$value[$keys[0]] .= '/' . $cfp;
		}
	}

	return $value;
}
add_filter(
	'request', 'custom_fields_permalink_request', 10, 1
);

function custom_fields_permalink_wp() {
	if ($GLOBALS['custom_fields_permalink_processing']) {
		$GLOBALS['more'] = 1;
		$GLOBALS['single'] = 1;

		global $wp_query;
		$wp_query->is_single = true;
	}
}
add_filter(
	'wp', 'custom_fields_permalink_wp', 0, 0
);

?>